KEY 103 has emerged victorious from an advertising battle with Salford-based rival Century 105.4.

Bosses at Key 103 complained to the Advertising Standards Authority after Capital-owned Century boasted on bus-side posters that its breakfast show - hosted by Tony Horn - was the biggest in the north west.

The complaint was upheld by the ASA, the independent, self-regulatory body for non-broadcast advertisements in the UK.

Paul Coleman, marketing manager at Key 103, said: ''The complaint referred to Century Radio's claim that they had the biggest breakfast show in the north west. Key 103 challenged this, using official industry research figures from Rajar and this has been upheld.''

ASA's decision to uphold the complaint marks the latest episode in a long history of rivalry between the stations since Century was launched by Border Radio Holdings.

It has always been difficult to assess the true performance of each radio station because they have different broadcasting footprints, with Key broadcasting to a Manchester audience and Century broadcasting across the north west.

Ambiguity

However, Key 103 - whose popular breakfast show is hosted by laddish double-act JK and Joel - is now bound to try to capitalise on the ASA decision in selling advertising.

An ASA spokesman said: ''The advertisers said the poster was intended to convey that Century FM was the biggest commercial radio station that covered the entire north west area of England; it was a regional, not a local station and covered the biggest geographical area.

''The advertisers sent their and five competitors' half yearly listener figures. The figures showed they had more listeners to the breakfast show than the radio stations listed.

''They explained that they had excluded the complainants from the comparison because Key 103 was a local radio station and did not cover an area as large as they did.

''The authority noted the advertisers' arguments and the play on words, but considered that, without further qualification or explanation the claim was ambiguous.''

The spokesman added: ''It considered that readers could infer that Century FM had more breakfast time listeners than every other radio station in the north west. Because it did not, the authority asked the advertisers to change the claim.''